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        <p><excerpt in="" index="" |="" 首页摘要=""><br><a id="more"></a></excerpt></p>
<the rest="" of="" contents="" |="" 余下全文="">

<p>WebRTC提供了点对点之间的通信，但并不意味着WebRTC不需要服务器。暂且不说基于服务器的一些扩展业务，WebRTC至少有两件事必须要用到服务器： </p>
<ol>
<li>浏览器之间交换建立通信的元数据（信令）必须通过服务器 </li>
<li>为了穿越NAT和防火墙</li>
</ol>
<p>此处，我们使用XMPP协议实现信令，采用openfire当做服务器，通过openfire服务器+Smack API实现信令的传递。</p>
<p>因此，在建立PeerConnection实例之后，想要使用其建立一个点对点的信道，我们需要做两件事： </p>
<ol>
<li>确定本机上的媒体流的特性，比如分辨率、编解码能力啥的（SDP描述符） </li>
<li>连接两端的主机的网络地址（ICE Candidate）</li>
</ol>
<hr>
<h3 id="通过offer和answer交换SDP描述符"><a href="#通过offer和answer交换SDP描述符" class="headerlink" title="通过offer和answer交换SDP描述符"></a>通过offer和answer交换SDP描述符</h3><p>大致上在两个用户（甲和乙）之间建立点对点连接流程应该是这个样子（这里不考虑错误的情况，PeerConnection简称PC）：</p>
<p>甲和乙各自建立一个PC实例<br>甲通过PC所提供的createOffer()方法建立一个包含甲的SDP描述符的offer信令<br>甲通过PC所提供的setLocalDescription()方法，将甲的SDP描述符交给甲的PC实例<br>甲将offer信令通过服务器发送给乙<br>乙将甲的offer信令中所包含的的SDP描述符提取出来，通过PC所提供的setRemoteDescription()方法交给乙的PC实例<br>乙通过PC所提供的createAnswer()方法建立一个包含乙的SDP描述符answer信令<br>乙通过PC所提供的setLocalDescription()方法，将乙的SDP描述符交给乙的PC实例<br>乙将answer信令通过服务器发送给甲<br>甲接收到乙的answer信令后，将其中乙的SDP描述符提取出来，调用setRemoteDescripttion()方法交给甲自己的PC实例</p>
<p>通过在这一系列的信令交换之后，甲和乙所创建的PC实例都包含甲和乙的SDP描述符了，完成了两件事的第一件。我们还需要完成第二件事——获取连接两端主机的网络地址</p>
<hr>
<h3 id="通过ICE框架建立NAT-防火墙穿越的连接"><a href="#通过ICE框架建立NAT-防火墙穿越的连接" class="headerlink" title="通过ICE框架建立NAT/防火墙穿越的连接"></a>通过ICE框架建立NAT/防火墙穿越的连接</h3><p>这个网络地址应该是能从外界直接访问，WebRTC使用ICE框架来获得这个地址。PeerConnection在创立的时候可以将ICE服务器的地址传递进去，如：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div></pre></td><td class="code"><pre><div class="line"> private List&lt;PeerConnection.IceServer&gt; getIceServers(String url,String user,String credential)</div><div class="line">&#123;</div><div class="line">    PeerConnection.IceServer turn = new PeerConnection.IceServer(</div><div class="line">                url,user,credential);</div><div class="line">    LinkedList&lt;PeerConnection.IceServer&gt; iceServers = new LinkedList&lt;PeerConnection.IceServer&gt;();</div><div class="line">    iceServers.add(turn);</div><div class="line">    return iceServers;</div><div class="line">&#125;</div><div class="line"></div><div class="line">//iceServer List对象获取</div><div class="line">List&lt;PeerConnection.IceServer&gt; iceServers = getIceServers(CoturnData.url,</div><div class="line">            CoturnData.userName,CoturnData.credential);</div><div class="line">pcConstraints = new MediaConstraints();</div><div class="line">pcConstraints.optional.add(new MediaConstraints.KeyValuePair(</div><div class="line">            &quot;DtlsSrtpKeyAgreement&quot;, &quot;true&quot;));</div><div class="line">pcConstraints.mandatory.add(new</div><div class="line">            MediaConstraints.KeyValuePair(&quot;VoiceActivityDetection&quot;, &quot;false&quot;));</div><div class="line">                </div><div class="line">pc = factory.createPeerConnection(iceServers,pcConstraints,pcObserver);</div></pre></td></tr></table></figure>
<p>当然这个地址也需要交换，还是以甲乙两位为例，交换的流程如下（PeerConnection简称PC）：</p>
<ol>
<li>甲、乙各创建配置了ICE服务器的PC实例，并为其添加onicecandidate事件回调</li>
<li>当网络候选可用时，将会调用onicecandidate函数</li>
<li>在回调函数内部，甲或乙将网络候选的消息封装在ICE Candidate信令中，通过服务器中转，传递给对方</li>
<li>甲或乙接收到对方通过服务器中转所发送过来ICE Candidate信令时，将其解析并获得网络候选，将其通过PC实例的addIceCandidate()方法加入到PC实例中</li>
</ol>
<p>这样连接就创立完成了，可以向RTCPeerConnection中通过addStream()加入流来传输媒体流数据。将流加入到RTCPeerConnection实例中后，对方就可以通过onaddstream所绑定的回调函数监听到了。调用addStream()可以在连接完成之前，在连接建立之后，对方一样能监听到媒体流</p>
<hr>
<p>代码实现：</p>
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class="line">409</div></pre></td><td class="code"><pre><div class="line">public class VideoCallActivity extends ParentActivity&#123;</div><div class="line">    public static final String VIDEO_TRACK_ID = &quot;video_track_id&quot;;</div><div class="line">    public static final String AUDIO_TRACK_ID = &quot;audio_track_id&quot;;</div><div class="line">    public static final String LOCAL_MEDIA_STREAM_ID = &quot;local_media_stream_id&quot;;</div><div class="line">    private String mServiceName;    //XMPP服务器名称</div><div class="line"></div><div class="line">    private GLSurfaceView mGLSurfaceView;</div><div class="line">    private GLSurfaceView mGLSurfaceViewRemote;</div><div class="line"></div><div class="line">    private PeerConnection pc;</div><div class="line">    private final PCObserver pcObserver = new PCObserver();</div><div class="line">    private final SDPObserver sdpObserver = new SDPObserver();</div><div class="line"></div><div class="line">    private MediaConstraints sdpMediaConstraints;</div><div class="line">    private MediaConstraints pcConstraints;</div><div class="line">    private String remoteName;</div><div class="line">    IceCandidate remoteIceCandidate;</div><div class="line"></div><div class="line">    private boolean mIsInited;</div><div class="line">    private boolean mIsCalled;</div><div class="line">    PeerConnectionFactory factory;</div><div class="line">    VideoCapturer videoCapturer;</div><div class="line">    VideoSource videoSource;</div><div class="line"></div><div class="line">    VideoRenderer localVideoRenderer;</div><div class="line">    VideoRenderer remoteVideoRenderer;</div><div class="line"></div><div class="line">    AudioManager audioManager;</div><div class="line"></div><div class="line">    @Override</div><div class="line">    protected void onCreate(Bundle savedInstanceState) &#123;</div><div class="line">        super.onCreate(savedInstanceState);</div><div class="line">        setContentView(R.layout.activity_video_call);</div><div class="line"></div><div class="line">        //打开扬声器</div><div class="line">        audioManager = (AudioManager) getSystemService(AUDIO_SERVICE);</div><div class="line">        audioManager.setSpeakerphoneOn(true);</div><div class="line"></div><div class="line">        mServiceName = connection.getServiceName();</div><div class="line">        mGLSurfaceView = (GLSurfaceView) findViewById(R.id.glsurfaceview);</div><div class="line">//        mGLSurfaceViewRemote = (GLSurfaceView) findViewById(R.id.glsurfaceview_remote);</div><div class="line">        //检查初始化音视频设备是否成功</div><div class="line">        if (!PeerConnectionFactory.initializeAndroidGlobals(this,true,true,true,null))</div><div class="line">        &#123;</div><div class="line">            Log.e(&quot;init&quot;,&quot;PeerConnectionFactory init fail!&quot;);</div><div class="line">            return;</div><div class="line">        &#125;</div><div class="line"></div><div class="line">//        Intent intent = getIntent().getBundleExtra()</div><div class="line"></div><div class="line">        //Media条件信息SDP接口</div><div class="line">        sdpMediaConstraints = new MediaConstraints();</div><div class="line">        //接受远程音频</div><div class="line">        sdpMediaConstraints.mandatory.add(new MediaConstraints.KeyValuePair(</div><div class="line">                &quot;OfferToReceiveAudio&quot;, &quot;true&quot;));</div><div class="line">        //接受远程视频</div><div class="line">        sdpMediaConstraints.mandatory.add(new MediaConstraints.KeyValuePair(</div><div class="line">                &quot;OfferToReceiveVideo&quot;, &quot;true&quot;));</div><div class="line"></div><div class="line">        factory = new PeerConnectionFactory();</div><div class="line"></div><div class="line">        //iceServer List对象获取</div><div class="line">        List&lt;PeerConnection.IceServer&gt; iceServers = getIceServers(CoturnData.url,</div><div class="line">                CoturnData.userName,CoturnData.credential);</div><div class="line">        pcConstraints = new MediaConstraints();</div><div class="line">        pcConstraints.optional.add(new MediaConstraints.KeyValuePair(</div><div class="line">                &quot;DtlsSrtpKeyAgreement&quot;, &quot;true&quot;));</div><div class="line">        pcConstraints.mandatory.add(new</div><div class="line">                MediaConstraints.KeyValuePair(&quot;VoiceActivityDetection&quot;, &quot;false&quot;));</div><div class="line">        pc = factory.createPeerConnection(iceServers,pcConstraints,pcObserver);</div><div class="line"></div><div class="line">        mIsInited = false;</div><div class="line">        mIsCalled=false;</div><div class="line"></div><div class="line">        boolean offer=getIntent().getBooleanExtra(&quot;createOffer&quot;,false);</div><div class="line">        //offer：如果offer为true表示主叫方初始化，如果为false表示被叫方初始化。</div><div class="line">        remoteName = getIntent().getStringExtra(&quot;remoteName&quot;);</div><div class="line">        if(!offer)</div><div class="line">        &#123;</div><div class="line">            initialSystem();</div><div class="line">        &#125;</div><div class="line">        else &#123;</div><div class="line">            callRemote(remoteName);</div><div class="line">        &#125;</div><div class="line">        //当VideoActivity已经打开时，处理后续的intent传过来的数据。</div><div class="line">        processExtraData();</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    @Override</div><div class="line">    protected void onNewIntent(Intent intent) &#123;</div><div class="line">        super.onNewIntent(intent);</div><div class="line">        setIntent(intent);</div><div class="line">        processExtraData();</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    @Override</div><div class="line">    protected void onDestroy() &#123;</div><div class="line">        super.onDestroy();</div><div class="line">        //通话结束，发送通话结束消息</div><div class="line">        videoCallEnded();</div><div class="line">        //释放资源</div><div class="line">        videoCapturer.dispose();</div><div class="line">        videoSource.stop();</div><div class="line">        if (pc != null) &#123;</div><div class="line">            pc.dispose();</div><div class="line">            pc = null;</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        audioManager.setSpeakerphoneOn(false);</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private void videoCallEnded() &#123;</div><div class="line">        String chatJid = remoteName+&quot;@&quot;+mServiceName;</div><div class="line">        Message message = new Message();</div><div class="line">        VideoInvitation videoInvitation = new VideoInvitation();</div><div class="line">        videoInvitation.setTypeText(&quot;video-ended&quot;);</div><div class="line">        message.addExtension(videoInvitation);</div><div class="line">        Chat chat = createChat(chatJid);</div><div class="line">        try &#123;</div><div class="line">            chat.sendMessage(message);</div><div class="line">        &#125; catch (SmackException.NotConnectedException e) &#123;</div><div class="line">            e.printStackTrace();</div><div class="line">        &#125;</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private void processExtraData() &#123;</div><div class="line">        Intent intent = getIntent();</div><div class="line">        //获取SDP数据</div><div class="line">        String sdpType = intent.getStringExtra(&quot;type&quot;);</div><div class="line">        String sdpDescription = intent.getStringExtra(&quot;description&quot;);</div><div class="line">        if (sdpType != null)</div><div class="line">        &#123;</div><div class="line"></div><div class="line">            SessionDescription.Type type = SessionDescription.Type.fromCanonicalForm(sdpType);</div><div class="line">            SessionDescription sdp = new SessionDescription(type,sdpDescription);</div><div class="line">            if (pc == null)</div><div class="line">            &#123;</div><div class="line">                Log.e(&quot;pc&quot;,&quot;pc == null&quot;);</div><div class="line">            &#125;</div><div class="line">            pc.setRemoteDescription(sdpObserver,sdp);</div><div class="line"></div><div class="line">            //如果是offer,则被叫方createAnswer</div><div class="line">            if (sdpType.equals(&quot;offer&quot;))</div><div class="line">            &#123;</div><div class="line">                mIsCalled = true;</div><div class="line">                pc.createAnswer(sdpObserver,sdpMediaConstraints);</div><div class="line">            &#125;</div><div class="line"></div><div class="line">        &#125;</div><div class="line"></div><div class="line">        //获取ICE Candidate数据</div><div class="line">        String iceSdpMid = intent.getStringExtra(&quot;sdpMid&quot;);</div><div class="line">        int iceSdpMLineIndex = intent.getIntExtra(&quot;sdpMLineIndex&quot;,-1);</div><div class="line">        String iceSdp = intent.getStringExtra(&quot;sdp&quot;);</div><div class="line">        if (iceSdpMid != null)</div><div class="line">        &#123;</div><div class="line">            IceCandidate iceCandidate = new IceCandidate(iceSdpMid,iceSdpMLineIndex,iceSdp);</div><div class="line"></div><div class="line">            if (remoteIceCandidate == null)</div><div class="line">            &#123;</div><div class="line">                remoteIceCandidate = iceCandidate;</div><div class="line">            &#125;</div><div class="line"></div><div class="line">            //下面这步放到函数drainRemoteCandidates()中</div><div class="line">            /*//添加远端的IceCandidate到pc</div><div class="line">            pc.addIceCandidate(iceCandidate);*/</div><div class="line">        &#125;</div><div class="line"></div><div class="line"></div><div class="line">        //结束activity</div><div class="line">        boolean videoEnded = intent.getBooleanExtra(&quot;videoEnded&quot;,false);</div><div class="line">        if (videoEnded)</div><div class="line">        &#123;</div><div class="line">            finish();</div><div class="line">        &#125;</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private void callRemote(String remoteName) &#123;</div><div class="line">        initialSystem();</div><div class="line">        //createOffer</div><div class="line">        pc.createOffer(sdpObserver,sdpMediaConstraints);</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private void initialSystem() &#123;</div><div class="line">        if (mIsInited)</div><div class="line">        &#123;</div><div class="line">            return;</div><div class="line">        &#125;</div><div class="line">        //获取前置摄像头本地视频流</div><div class="line">        String frontDeviceName = VideoCapturerAndroid.getNameOfFrontFacingDevice();</div><div class="line">//        String frontDeviceName = &quot;Camera 1, Facing front, Orientation 0&quot;;</div><div class="line">        Log.e(&quot;CameraName&quot;,&quot;CameraName: &quot;+frontDeviceName);</div><div class="line">        videoCapturer = VideoCapturerAndroid.create(frontDeviceName);</div><div class="line">        if (videoCapturer == null)</div><div class="line">        &#123;</div><div class="line">            Log.e(&quot;open&quot;,&quot;fail to open camera&quot;);</div><div class="line">            return;</div><div class="line">        &#125;</div><div class="line">        //视频</div><div class="line">        MediaConstraints mediaConstraints = new MediaConstraints();</div><div class="line">        videoSource = factory.createVideoSource(videoCapturer, mediaConstraints);</div><div class="line">        VideoTrack localVideoTrack = factory.createVideoTrack(VIDEO_TRACK_ID, videoSource);</div><div class="line"></div><div class="line">        //音频</div><div class="line">        MediaConstraints audioConstraints = new MediaConstraints();</div><div class="line">        AudioSource audioSource = factory.createAudioSource(audioConstraints);</div><div class="line">        AudioTrack localAudioTrack = factory.createAudioTrack(AUDIO_TRACK_ID,audioSource);</div><div class="line"></div><div class="line">        Runnable runnable = new Runnable() &#123;</div><div class="line">            @Override</div><div class="line">            public void run() &#123;</div><div class="line"></div><div class="line">            &#125;</div><div class="line">        &#125;;</div><div class="line">        VideoRendererGui.setView(mGLSurfaceView,runnable);</div><div class="line">        try &#123;</div><div class="line">            //改成ScalingType.SCALE_ASPECT_FILL可以显示双方视频，但是显示比例不美观，并且不知道最后一个参数true和false的含义。</div><div class="line">            localVideoRenderer = VideoRendererGui.createGui(0,0,30,30, VideoRendererGui.ScalingType.SCALE_ASPECT_FILL,true);</div><div class="line">            remoteVideoRenderer = VideoRendererGui.createGui(0,0,100,100, VideoRendererGui.ScalingType.SCALE_FILL,true);</div><div class="line">            localVideoTrack.addRenderer(localVideoRenderer);</div><div class="line">        &#125; catch (Exception e) &#123;</div><div class="line">            e.printStackTrace();</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        MediaStream localMediaStream = factory.createLocalMediaStream(LOCAL_MEDIA_STREAM_ID);</div><div class="line">        localMediaStream.addTrack(localAudioTrack);</div><div class="line">        localMediaStream.addTrack(localVideoTrack);</div><div class="line"></div><div class="line">        pc.addStream(localMediaStream);</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private List&lt;PeerConnection.IceServer&gt; getIceServers(String url,String user,String credential)</div><div class="line">    &#123;</div><div class="line">        PeerConnection.IceServer turn = new PeerConnection.IceServer(</div><div class="line">                url,user,credential);</div><div class="line">        LinkedList&lt;PeerConnection.IceServer&gt; iceServers = new LinkedList&lt;PeerConnection.IceServer&gt;();</div><div class="line">        iceServers.add(turn);</div><div class="line">        return iceServers;</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private class PCObserver implements PeerConnection.Observer</div><div class="line">    &#123;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onSignalingChange(PeerConnection.SignalingState signalingState) &#123;</div><div class="line"></div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onIceConnectionChange(PeerConnection.IceConnectionState iceConnectionState) &#123;</div><div class="line"></div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onIceGatheringChange(PeerConnection.IceGatheringState iceGatheringState) &#123;</div><div class="line"></div><div class="line">        &#125;</div><div class="line"></div><div class="line">        //发送ICE候选到其他客户端</div><div class="line">        @Override</div><div class="line">        public void onIceCandidate(final IceCandidate iceCandidate) &#123;</div><div class="line">            //利用XMPP发送iceCandidate到其他客户端</div><div class="line">            runOnUiThread(new Runnable() &#123;</div><div class="line">                @Override</div><div class="line">                public void run() &#123;</div><div class="line">                    String chatJid = remoteName+&quot;@&quot;+mServiceName;</div><div class="line">                    Message message = new Message();</div><div class="line">                    IceCandidateExtensionElement iceCandidateExtensionElement=</div><div class="line">                            new IceCandidateExtensionElement();</div><div class="line">                    iceCandidateExtensionElement.setSdpMidText(iceCandidate.sdpMid);</div><div class="line">                    iceCandidateExtensionElement.setSdpMLineIndexText(iceCandidate.sdpMLineIndex);</div><div class="line">                    iceCandidateExtensionElement.setSdpText(iceCandidate.sdp);</div><div class="line">                    message.addExtension(iceCandidateExtensionElement);</div><div class="line">                    Chat chat = createChat(chatJid);</div><div class="line">                    try &#123;</div><div class="line">                        chat.sendMessage(message);</div><div class="line">                    &#125; catch (SmackException.NotConnectedException e) &#123;</div><div class="line">                        e.printStackTrace();</div><div class="line">                    &#125;</div><div class="line"></div><div class="line">                &#125;</div><div class="line">            &#125;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        //Display a media stream from remote</div><div class="line">        @Override</div><div class="line">        public void onAddStream(final MediaStream mediaStream) &#123;</div><div class="line">            runOnUiThread(new Runnable() &#123;</div><div class="line">                @Override</div><div class="line">                public void run() &#123;</div><div class="line">                    if (pc == null)</div><div class="line">                    &#123;</div><div class="line">                        Log.e(&quot;onAddStream&quot;,&quot;pc == null&quot;);</div><div class="line">                        return;</div><div class="line">                    &#125;</div><div class="line">                    if (mediaStream.videoTracks.size()&gt;1 || mediaStream.audioTracks.size()&gt;1)</div><div class="line">                    &#123;</div><div class="line">                        Log.e(&quot;onAddStream&quot;,&quot;size &gt; 1&quot;);</div><div class="line">                        return;</div><div class="line">                    &#125;</div><div class="line">                    if (mediaStream.videoTracks.size() == 1)</div><div class="line">                    &#123;</div><div class="line">                        VideoTrack videoTrack = mediaStream.videoTracks.get(0);</div><div class="line">                        videoTrack.addRenderer(remoteVideoRenderer);</div><div class="line">                    &#125;</div><div class="line">                &#125;</div><div class="line">            &#125;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onRemoveStream(final MediaStream mediaStream) &#123;</div><div class="line">            runOnUiThread(new Runnable() &#123;</div><div class="line">                @Override</div><div class="line">                public void run() &#123;</div><div class="line">                    mediaStream.videoTracks.get(0).dispose();</div><div class="line">                &#125;</div><div class="line">            &#125;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onDataChannel(DataChannel dataChannel) &#123;</div><div class="line"></div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onRenegotiationNeeded() &#123;</div><div class="line"></div><div class="line">        &#125;</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    private class SDPObserver implements SdpObserver</div><div class="line">    &#123;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onCreateSuccess(final SessionDescription sessionDescription) &#123;</div><div class="line">            //sendMessage(offer);</div><div class="line">            runOnUiThread(new Runnable() &#123;</div><div class="line">                @Override</div><div class="line">                public void run() &#123;</div><div class="line">                    String chatJid = remoteName+&quot;@&quot;+mServiceName;</div><div class="line">                    Message message = new Message();</div><div class="line">                    SDPExtensionElement sdpExtensionElement = new SDPExtensionElement();</div><div class="line">                    sdpExtensionElement.setTypeText(sessionDescription.type.canonicalForm());</div><div class="line">                    sdpExtensionElement.setDescriptionText(sessionDescription.description);</div><div class="line">                    message.addExtension(sdpExtensionElement);</div><div class="line">                    Chat chat = createChat(chatJid);</div><div class="line">                    try &#123;</div><div class="line">                        chat.sendMessage(message);</div><div class="line">                    &#125; catch (SmackException.NotConnectedException e) &#123;</div><div class="line">                        e.printStackTrace();</div><div class="line">                    &#125;</div><div class="line"></div><div class="line">                    pc.setLocalDescription(sdpObserver,sessionDescription);</div><div class="line">                &#125;</div><div class="line">            &#125;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onSetSuccess() &#123;</div><div class="line">            runOnUiThread(new Runnable() &#123;</div><div class="line">                @Override</div><div class="line">                public void run() &#123;</div><div class="line">                    //主叫方</div><div class="line">                    if (!mIsCalled)</div><div class="line">                    &#123;</div><div class="line">                        if (pc.getRemoteDescription() != null)</div><div class="line">                        &#123;</div><div class="line">                            drainRemoteCandidates();</div><div class="line">                        &#125;</div><div class="line">                    &#125;</div><div class="line">                    //被叫方</div><div class="line">                    else</div><div class="line">                    &#123;</div><div class="line">                        //如果被叫方还没有createAnswer</div><div class="line">                        if (pc.getLocalDescription() == null)</div><div class="line">                        &#123;</div><div class="line">                            Log.e(&quot;SDPObserver&quot;, &quot;SDPObserver create answer&quot;);</div><div class="line">                        &#125;</div><div class="line">                        else</div><div class="line">                        &#123;</div><div class="line">                            drainRemoteCandidates();</div><div class="line">                        &#125;</div><div class="line">                    &#125;</div><div class="line">                &#125;</div><div class="line">            &#125;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        private void drainRemoteCandidates() &#123;</div><div class="line">            if (remoteIceCandidate == null)</div><div class="line">            &#123;</div><div class="line">                Log.e(&quot;SDPObserver&quot;,&quot;remoteIceCandidate == null&quot;);</div><div class="line">                return;</div><div class="line">            &#125;</div><div class="line">            pc.addIceCandidate(remoteIceCandidate);</div><div class="line">            Log.e(&quot;IceCanditate&quot;,&quot;添加IceCandidate成功&quot;);</div><div class="line">            remoteIceCandidate = null;</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onCreateFailure(String s) &#123;</div><div class="line">            Log.e(&quot;SDPObserver&quot;,&quot;onCreateFailure&quot;);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        @Override</div><div class="line">        public void onSetFailure(String s) &#123;</div><div class="line">            Log.e(&quot;SDPObserver&quot;,&quot;onSetFailure&quot;);</div><div class="line">        &#125;</div><div class="line">    &#125;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
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        <p><span>本文标题:</span><a href="/Communication/WebRTC/Android之WebRTC介绍（二）/">Android之WebRTC介绍（二）</a></p>
        <p><span>文章作者:</span><a href="/" title="回到主页">FreeShow</a></p>
        <p><span>发布时间:</span>2016-07-23, 22:16:13</p>
        <p><span>最后更新:</span>2017-03-28, 17:03:50</p>
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            <span>原始链接:</span><a class="post-url" href="/Communication/WebRTC/Android之WebRTC介绍（二）/" title="Android之WebRTC介绍（二）">https://freeshow.github.io/Communication/WebRTC/Android之WebRTC介绍（二）/</a>
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